What format are the calculators in?
Excel (.xlsx). They open natively in Excel, and work in Google Sheets and Numbers too — some formatting may look slightly different outside Excel.
How do I get the file after I pay?
You're redirected straight to a download page the moment payment completes. No account, no waiting, no email required — though a copy of the receipt is sent to the email you check out with.
Do you offer refunds?
If a calculator has an error or doesn't do what its product page describes, you'll get a full refund — just get in touch. Because these are instant-download digital files, refunds aren't offered for a simple change of mind.
Will I be charged again later?
No. Every purchase is a single, one-time payment. There are no subscriptions or recurring charges anywhere in this shop.
What happens when the underlying rules change?
Calculators that depend on rates or standards (like tax) are dated to a specific year. When those change, a new version is published separately rather than updated underneath existing buyers.
Can I use these for an official filing or submission?
No — these are simplified planning estimators, not official filing tools or professional advice. Each product page states exactly what's included. For anything you're filing or submitting, confirm the numbers with a qualified professional.
I found a number that looks wrong. What do I do?
Get in touch right away. Every calculator is sourced and verified before it's sold, but if something looks off, it gets checked and corrected as a priority.
How do I contact you?
Email rumblechow@gmail.com for questions, refunds, or anything that looks off — we usually reply within a couple of business days. See our Terms & Refunds for the full policy.