How to Budget for Shared Household Supplies With a Split Cap

Pick your model

Choose one model that fits your situation, write it down, and treat it as “the rule” until something meaningfully changes (income shifts, moving, a new recurring cost).

Model A: Equal split + cap
Best if you earn similar amounts, prefer simplicity, and don’t want to debate every receipt.

Model B: Proportional split + cap (by net income)
Best if incomes differ and you want the share to feel fair without tracking who used what.

Model C: Roles-based split + cap (one pays categories)
Best if you like clear ownership (one person handles supplies, the other handles another joint category) while keeping total burden balanced.

No model is “more mature.” The best one is the one you can follow without scorekeeping.

Define “shared household supplies” (so you don’t argue later)

Keep the shared list tight and boring. Think: things that keep the home running.

Shared essentials (usually included):

Cleaning products, laundry detergent, dishwasher tabs
Toilet paper, paper towels, trash bags
Basic light bulbs, batteries, small home maintenance items
Dish soap, sponges, kitchen foil/parchment

Personal treats (usually excluded):

Premium skincare, specialty supplements, hobby gear
Individual snacks/drinks you don’t both use
“Just for me” upgrades (fancy candles, luxury versions) unless you both agree

Copy-paste definition

“Shared household supplies are non-food consumables and small maintenance items used by both of us to keep the home clean, safe, and functioning. Personal treats are paid individually unless we both opt in.”

The split cap: the rule that prevents resentment

A split cap is a ceiling on how much each person contributes to shared supplies, expressed as a percent of take-home pay. This keeps supplies from quietly expanding into a fairness fight.

How it works

Agree a monthly supplies target (based on what you typically use).
Set a cap for each person as a percent of take-home pay.
If supplies push beyond the total cap, you don’t debate worthiness item-by-item—you use a pre-agreed option.

Copy-paste cap rule

“Each of us contributes up to X% of take-home pay toward shared household supplies. If we hit the cap, we pause upgrades and choose one overflow option we already agreed on.”

Three fairness options when you hit the cap

Pick one option now, so you don’t have to negotiate when tired.

Option 1: Trim first (most peaceful)

“If we hit the cap, we switch to basics only until the next restock cycle: store brand, fewer extras, no ‘nice-to-have’ upgrades.”

Option 2: Upgrade vote (most collaborative)

“If we hit the cap, we choose one upgrade we both care about and drop the rest.”

Option 3: Personal add-ons (most flexible)

“If we hit the cap, essentials stay shared, and any extras are personal treats paid by the person who wants them.”

Copy-paste rules for each model

Model A: Equal split + cap

“We split shared household supplies 50/50.”
“Each person’s maximum contribution is X% of take-home pay.”
“Supplies are bought from the joint pot; if the pot is low, we follow our cap overflow option.”

Model B: Proportional split + cap (recommended when incomes differ)

“We split shared household supplies proportionally by net income (example: 60/40 if our take-home is 60/40).”
“Each person’s maximum contribution is X% of take-home pay.”
“We don’t track who used what; we track only the category total.”

Model C: Roles-based split + cap

“One person manages buying shared household supplies; the other manages another joint category of similar size.”
“We still apply a cap: each person’s contribution across joint categories stays under X% of take-home pay.”
“If either role becomes consistently heavier, we swap roles or rebalance the split.”

A simple system that doesn’t require policing

Choose the lightest setup you can actually maintain:

System 1: Joint supplies pot

One shared account or envelope labeled “Household Supplies.”
Purchases come from it, not from personal cards.

System 2: One card, one tracker

One person pays, the other transfers their share, and you record only the total and split (not every item).

Copy-paste “no policing” rule

“We assume good intent. We don’t question individual items in the shared essentials list. We only revisit the list if something repeatedly creates tension.”

Conversation prompts (use these in one sitting)

“What items feel like true essentials for both of us?”
“What counts as a personal treat, even if it’s used at home?”
“When we hit the cap, do we prefer trimming, voting, or personal add-ons?”
“Do we want a proportional split, or is simplicity more valuable right now?”

If this feels hard, start here

Use Model B with a conservative cap and a tight essentials list:

“We split supplies by net-income ratio.”
“Each of us contributes up to X% of take-home pay.”
“If we hit the cap, we switch to basics only and move any extras to personal treats.”